Field
The present disclosure relates generally to electronic circuit designs, and more particularly, to an apparatus and method related to analog-to-digital converters and delta-sigma modulators.
Background
Delta-sigma modulators and other types of analog-to-digital converters (ADCs) are widely used in communication systems and in many other applications. In communication systems, for example, such devices may be used to convert an intermediate frequency (IF) signal to a baseband frequency signal, in order to meet dynamic range requirements for digital signal processing, and to provide improved adaptability and programmability to receiver circuitry. The advantages of delta-sigma modulators include high dynamic range, which is often needed to distinguish a small desired signal from blockers and interferers. Delta-sigma modulators shape the quantization noise out-of-band, and allow combining decimation filtering with selective digital filtering and IF mixing to attenuate both the quantization noise and neighboring blockers. In addition, the ability to select different sampling rates in the delta-sigma modulator architecture allows a single device to be adapted to different requirements, for example, the requirements imposed by multiple RF standards. Moreover, the use of higher sampling rates and complex digital signal processing allow delta-sigma converters to exhibit relatively low sensitivity to interfering analog signals.
One-over-f (1/f) noise is one type of noise at the output of a typical converter (which word herein applies to delta-sigma modulators and ADCs). One-over-f noise is difficult to reduce because it lies in the same band as the converted signal, making it difficult to filter the noise out of the converted signal. Generally, reducing such noise is costly in terms of chip area and power consumption.
Size, power consumption, speed, signal-to-noise (SNR), and production costs loom large in designing electronic equipment, and especially portable battery-operated electronic equipment such as wireless access terminals. Therefore, there is a need in the art to improve SNR and reduce the power consumption of electronic equipment, including delta-sigma modulators and ADCs. There is also a need in the art to decrease size and weight of electronic equipment, including delta-sigma modulators and ADCs. There is a further need in the art to lower the cost of manufacturing electronic equipment, including delta-sigma modulators and other devices that include integrators and summers.